This section provides background information related to the present disclosure which is not necessarily prior art.
Oxygen masks are connected to a source of oxygen that is delivered directly to the patient's airway, namely, the nose and mouth. Conventional oxygen masks generally cover the entire nose and mouth areas and have no apertures to allow surgical tools to access the mouth or nose. Notwithstanding the ability of conventional masks to form a seal about the patient's airway, and attempt to confine the area about the airway to which oxygen is delivered, conventional masks suffer from numerous drawbacks. In particular, most conventional oxygen masks have a tendency to dilute the oxygen being delivered to the patient. Also, those masks cause oxygen to be dispersed about and away from the patient's airway, which can lead to ineffective oxygen delivery.
Nasal cannulation can be deployed to compensate for the patient's inability to breathe through his or her mouth. However, this approach has problems. For example, nasal cannulation delivers oxygen typically ineffectively and wastefully. The structure and function of most conventional oxygen masks assume that the patient undergoing the procedure will breathe in oxygen precisely as delivered. Additionally, this approach assumes that infusing sufficiently large volumes of oxygen will, in fact, ultimately reach the patient. The logic is flawed. Due to the dilution and dispersion of the oxygen being delivered by conventional masks, this practice is extremely wasteful. Attempting to deliver oxygen in the aforementioned manner wastes considerable amounts of oxygen that must be constantly delivered throughout the entire respiratory cycle. Only a very small portion of the oxygen is delivered to the patient.
In an attempt to address the foregoing issues, a specific type of oxygen mask/delivery system has been developed that essentially deploys a “face tent”. After the patient assumes the lateral decubitus or prone position, a plastic sheet or bag is used to cover the patient's face, following nasal cannulation. The plastic sheet or bag is operative to define a tent over the airway that maintains a reservoir of oxygen supposedly made available to the patient. These modified oxygen masks, often referred to as the TSE mask, has been discussed in Shaul Cohen, et al., “TSE ‘Mask’ Improves Oxygenation in Deeply Sedated Patients with Nasal Cannula during Upper Endoscopy.” Anesthesiology 107:A922, 2007. Poster Presentation at American Society of Anesthesiologists Annual Meeting, October 2007, Chicago, Ill.
The TSE mask is designed to improve effectiveness at inhibiting oxygen desaturation. First, the oxygen reservoir of the TSE mask can provide an inspiratory fraction of oxygen of 40-60% with oxygen flows of 4 L/min. Accordingly, titrating intravenous sedatives after pre-oxygenation can achieve moderate-to-deep sedation while maintaining spontaneous respiration without oxygen desaturation. Second, the patient's respirations are monitored with capnography or a pediatric precordial stethoscope placed over the trachea. Thus, if the patient becomes apneic because of airway obstruction or over-sedation, medical personnel still have an average of two to three minutes to manipulate the airway before oxygen desaturation occurs.
Furthermore, conventional masks are typically ill-suited for use in upper endoscopy procedures that require the surgical instrumentation be deployed through the mouth and throat of the patient. For example, conventional masks do not include a sufficient aperture to allow surgical tools to access the mouth or nose. In this regard, the oxygen mask needs to effectively deliver oxygen, while having an opening or orifice through which surgical instrumentation can be deployed. The opening or orifice in the mask must have enough flexibility to enable the instrumentation to be easily and readily manipulated, as occurs when instrumentation is deployed in upper endoscopy procedures.
In attempt to introduce an oxygen mask suitable for allowing surgical tools to access the mouth and nose during upper endoscopy procedures, a specific type of oxygen mask/delivery system has been developed. These surgical masks, often referred to as the Panoramic Oxygen Mask (“POM”) has been discussed in U.S. Pat. No. 8,960,195 to Lehman. U.S. Pat. No. 8,960,195 describes an intubation-facilitating oxygen mask that can be worn during standard oxygen therapy. This mask is intended to provide for increased oxygen saturation and continuous monitoring of carbon dioxide of expired gases. This mask introduces an aperture in the mask above the mouth to allow surgical tools to access the mouth and nose during upper endoscopy procedures.
Although some conventional masks are designed for upper endoscopy procedures, these conventional masks still present health risks. For example, conventional masks designed for upper endoscopy procedures provide sub-optimal monitoring of patients. In 80% or more cases when patients are sedated, an anesthesiologist may not be present in the procedure room. In such situations, nurses generally monitor the patient for oxygenation status and breathing status in addition to their normal workload (e.g., paper work, administration of medication, following orders from endoscopists or other physicians, securing agitated and/or thrashing patients). Indications of breathing can include: level of consciousness (e.g., spoken response to commands can determine the patient's level of consciousness), visual breathing signs, vital signs (e.g., blood pressure, heart rate), EKG, oxygen saturation (oximetry), and CO2 levels. However, determining all of these indications can occur in dark conditions or settings with less light, which can reduce accurate monitoring of patient breathing and oxygenation statuses.
When conventional masks designed for upper endoscopy use nasal cannula for oxygen supplementation, an end tidal CO2 machine is typically used to monitor breathing. To measure the oxygen condition of the patient, a finger monitor is typically used. However, these monitoring techniques are problematic. For example, the CO2 monitoring machine uses the same or similar alarm when a negative occurrence is detected. Therefore, the alarm sound of the CO2 monitoring machine will not specify to the caretaker whether the patient is breathing, O2 saturation is low, or any other number of reasons that trigger the alarm. Further, the CO2 monitoring machine does not indicate what caused the trigger. For example, if O2 saturation is low, the caretaker still has to determine whether it was because the patient is breathing through the mouth or for some other reason. Each reason that can trigger the alarm can have a different appropriate response. If the patient has too little oxygen in the body, then the O2 flow rate can be increased to provide more oxygen. If the patient's airway is obstructed, then the airway must be opened. Without knowing the cause of the alarm, caretakers must take time to identify the cause. In many cases, false alarms can be triggered by events such as the patient thrashing, further making it harder for caretakers to respond appropriately and disturbing the working environment. The net effect of the CO2 monitoring techniques of conventional oxygen masks designed for upper endoscopy procedures is compromised patient safety.
Despite various attempts to improve upon other conventional masks, all conventional masks (including masks designed for upper endoscopy procedures) have one or more of the following safety and effectiveness related issues: air entrainment, re-breathing of mechanical dead space air, no effective sequential oxygen delivery system, wasting of oxygen (or other target gas or drug), ineffective monitoring of expired gases for early recognition of undesired events, bulkiness, and high cost.
It has been recognized that there is a substantial need for an oxygen mask that can more efficiently and effectively provide oxygen enriched gas to be more readily taken in by a patient's airway while the patient breathes while wearing the oxygen mask (e.g., while during surgery).
There is a further need for such an oxygen mask that can improve monitoring of patients undergoing upper endoscopy procedures for early detection and prevention of oxygen desaturation or other undesired events.
There is a further need for such an oxygen mask that can make available a reservoir of oxygen enriched air immediately adjacent the patient's airway upon the uptake of a breath by the patient to a degree greater than conventional oxygen masks.
Moreover, there is a need for such a mask that can continuously maintain an enriched source of oxygen as maintained in a reservoir immediately accessible to the patient's airway while at the same time consuming substantially less amounts of oxygen than prior art oxygen masks.
There is still a further need for such an oxygen mask that is of simple construction, easy to deploy, can be readily used with nasal cannulation, and can be utilized on patients undergoing upper endoscopy procedures such that instrumentation can be deployed through such mask with relative ease and flexibility.